Refrigeration



y 1943. c. E. PLOEGER 2,320,097

REFRIGERATION 1 Filed Au 20, 1941 Y 2% B V A; AT'TORNEY Patented May 35,1943

Clyde E. Ploeger, Evansville, Servel, Inc., New York, N.

Delaware Iml, assignoi: to, Y., a corporation of Application August 20, 1941, Serial No. 407,519

8'Claims.

This invention relates to compression type refrigerating systems, and it is an object of the invention to provide an improved multiple-stage compression type refrigerating system which is capable of producing relatively low temperatures efficiently and economically.

When itis desired to produce relatively low temperatures by means of a compression type refrigerating system, it is expedient to utilize multiple-stage compression of refrigerant vapor, and to effect cooling of'the refrigerant gas between the two or more stages of compression. Such cooling may be effected byeVaporation of refrigerant in such a system at a pressure higher than that of the evaporator and lower than that of the condenser.

I provide a system of refrigeration embodying I these known concepts, but having new structure and relationship of parts useful to provide heat interchange at a. relatively 'high rate in a small space, and to permit the use of a high temperature evaporator which need not be insulated.

The accompanyingdrawing shows more or less diagrammatically a refrigerating system embodying my invention. 1

The numeral I designates a low temperature evaporator of any desired construction or type, illustrated as employed to maintain a relatively low temperature within an enclosure 2 having a wall 3. Refrigerant liquid is supplied to evapo- 1 ratorl through supply line 4, and is admitted to the evaporator under the control of an expansion valve type, but whichis preferably adapted, in combination with thermal bulb Ii, attached to suction line 'I and in heat exchange relation therewith, to control in heat of refrigerant vapor passing'from the evaporator.

Suction line I delivers refrigerant vapor to manifold 8, compressor cylinders 9, operating inmultiple arrangement. 'As illustrated, the low pressure cylinders 9, and high pressure compressor cylinder ID, are integral parts of a unitary compressor apparatus driven through shaft II by any suitable means, such as an electric to be understood that the invention is not limited to the use of such unitary compressor apparatus, or any particular number or arrangement of motor, but it is.

5, which may be of any desired conventional manner the superserving the intakes to low-pressure refrigerant within evaporator provide the desired degree of passing from the open end It up through such liquid.

Vapor is relieved from the top of evaporator I5 through outlet I 6 and coil I'I disposed exteriorly of high temperature evaporator I5 but withinrefrigerant liquid receiver I8, so that the gas in such coil is in heat of line I3 bubbles exchange relation with refrigerant liquid con-- tained within receiver I8; This heat exchange desirably cools such refrigerant liquid, and insures against the entry of particles of liquid refrigerant into compressor cylinder I0, by vaporizing any such liquid particles as may be entrained by the gas passing through outlet It. The refrigerant gas leaving coil I1 passes through line I9 to the intake of high-pressure compressor cylinder Ill.

The gas passing through pipe I9 will be substantially cooler than the gas passing to evaporator I5 through line I3. 'This cooling of the refrigerant vapor discharged from the cylinders 9, prior to its delivery to high-pressure cylinder III, serves substantially to increase the'volumetric efficiency of the compressor.

The refrigerant vapor discharged at relatively high pressure from cylinder III is delivered through line 20 to condenser 2I, which may be of any desired type or construction, where. it is liquefied. The resultant condensate is delivered throughline 22. to the upper end of liquid receiver i 8, and, after circulating therethrough in heat exchange relation with high-temperature evaporator I5 and coil I1, is relieved from the bottom of receiver I8through line 23, which discharges into high temperature evaporator I5. Expansion valve24 controls the admission of refrigerant from the receiver, which is at high pressure, to the evaporator I5, which is at a lower pressure. Expansion valve 24 is under thecontrol of thermal bulb 25, t ermally bonded to line I9, preferably, at the po' t where such line passes out of receiver I8, so that the evaporation of I5 is controlled to superheat in the refrigerant vapor passing to the intake of the high pressure stage of the compressor.

compressor stages, but may be embodied in any system utilizing stage compression of refrigerant.

Refrigerant gas delivered from the low pressure cylinders 9 is received withinmanifold l2 and thence passes through line I3, within and terminates proximate the bottom of a receptacle I5 serving as a high temperature evaporator. When the system is operative in the intended manner, evaporator I5 contains refrigerant liquid, and the refrigerant vapor which projects Since the pressure within evaporator I5 is lower than that within receiver I8, some of the refrigerant liquid admitted to the evaporator through line 23 evaporates, forming what is known as flash gas. The evaporation of such portion of the refrigerant admitted through line 23 serves to cool the remainder, so'that the re-' frigerant liquid within evaporator I5 is at a lower temperature than that within receiver I8 but outside of the evaporator I5.

The flash gas" formed in evaporate" 3 'I5 is relieved therefrom through outlet I6, alo g with the refrigerant vapor supplied within the evap- Refrig'erant liquid is reis routed through a erating cycle.

lieved from the bottom of high temperature evaporator l5 through supply line 4, which, as set forth above, supplies it to the low temperature evaporator I, thus completing the refrig- Since evaporator i5 is formed of material having relatively high heat conductivity, there is effected'a substantial transfer of heat between the relatively cool liquid within the evaporator and the refrigerant liquid immediately surrounding such evaporator. Such pre-cooling of the refrigerant in receiver l8 will be appreciated as being extremely desirable when it is realized that all cooling of refrigerant liquid which can beefiected before the refrigerant is expanded at the point where the useful work of refrigeration is to be accomplished permits greater operating ef'ficiency and greater refrigerative effect at such point. For the same reason, the further cooling of refrigerant liquid within high temperature evaporator l5 by evaporation of a portion thereof serves to promote efficiency of the system.

If desired, test valves 26 and 21 may be provided, the former serving receiver l8 and the latter, through tube 28, serving high temperature evaporator 15.

Various changes and modifications may be made within the scope of the invention as set forth in the following claims.

What is claimed is:

1. Refrigerating apparatus comprising a multiple stage compressor, a condenser, a receiver, a low temperature evaporator, a high temperature evaporator arranged in heat exchange relation with said receiver, a conduit including a pressure reducing valve for conducting liquid from said receiver to said high temperature evaporator, and a second conduit including a second pressure reducing valve for conducting liquid from said high temperature evaporator to said low temperature evaporator.

2. In a refrigerating apparatus comprising a low-temperature evaporator, a condenser, and a multiple stage compressor, the combination of a liquid receiver receiving refrigerant liquid from said condenser, and a high-temperature evaporator disposed within said receiver and receiving refrigerant liquid therefrom and supplying liquid refrigerant to said low-temperature evaporator, said high-temperature evaporator being connected to the outlet of a low pressure stage of said compressor apparatus and receiving gas discharged therefrom, and being connected also to the inlet of a high pressure stage of said compressor apparatus and supplying gas thereto.

3. In a refrigerating apparatus comprising a low-temperature evaporator, a condenser, and a multiple stage compressor, the combination of a liquid receiver receiving refrigerant liquid from said condenser, and a high-temperature evaporator disposed within said receiver and receiving refrigerant liquid therefrom and supplying liquid refrigerant to said low-temperature evaporator, said high-temperature evaporator being connected to the outlet of a low pressure stage of said compressor apparatus and receiving gas discharged therefrom, and being connected also 1 to the inlet of a high'pressure stage of said compressor apparatus and supplying gas thereto, and a valve regulating the supply of refrigerant'liquid to said high temperature'evaporator from' said receiver in accordance with variations in the temperature of gas passing to the inlet of said high pressure stage of said compressor apparatus.

4. In a refrigerating apparatus comprising a low-temperature evaporator, a condenser, and a multiple stage compressor, the combination ofa liquid receiver receiving refrigerant liquid from said condenser, and a high-temperature evaporator disposed Within said receiver and receiving refrigerant liquid therefrom and supplying liquid refrigerant to said low-temperature evaporator, said high-temperature evaporator beingconnected to the outlet of a low pressure stage of said compressor apparatus and receiving gas discharged therefrom, and being connected also to the inlet of a high pressure stage of said compressor apparatus and supplying gas thereto, the connection between said high-temperature evaporator and the inlet of said high, pressure stage of said compressor apparatus including a conduit disposed without said high-temperature evaporator and within said receiver, whereby refrigerant flowing through said conduit from said evaporator receives heat from refrigerant liquid in said receiver, cooling such liquid, and whereby the passage of refrigerant liquid to said compressor apparatus is avoided.

5. In a refrigerating apparatus comprising a low temperature evaporator, a condenser and a compressor, a liquid receiver adapted to receive condensed refrigerant from said condenser, and a high temperature evaporator wholly contained within said receiver and adapted to receive refrigerant liquid therefrom, said high temperature evaporator being provided with an outlet in an upper portion thereof communicating with'said compressor, and with another outlet in a lower portion thereof communicating with said low temperature evaporator,

pressure stage of said compressor apparatus for delivery of gas thereto, and a device to control flow of refrigerant from said receiver into said high temperature evaporator 'at a pressure corresponding substantially to the pressure at the inlet to said high pressure stage, whereby refrigerant passing from said receiver to said high temperature evaporator is subjected to a reduction of pressure in consequence of which a portion of such refrigerant is evaporated, said high temperature evaporator being connected to said low temperature evaporator and supplying relativel'y cool liquid refrigerant thereto for evaporation therein at reduced pressure corresponding substantially to'the pressure at the inlet to said low pressure stage of said compressor apparatus.

7. Refrigerating apparatus as set forth in claim 1 in which said high temperature evaporator is located within said receiver.

8. Refrigerating apparatus as set forth in claim 1 in which said high temperature evaporator is located within said receiver, and said'pressure reducing valves are thermostatic expansion valves.

CLYDE E. PLOEGER. 

